A device for emptying a film tube containing a pasty substance and having the features recited in the preamble of claim 1 is known from German Utility Model No. 9,103,038. In the known device, a blade with a face extending transversely of the radial direction of the tube is used for rupturing the tube. For emptying the tube, pressure is exerted on the rear end thereof, which pressure progresses through the tube content and urges the front end of the tube against the oblique edge of the blade. Due to this action, a fold present at the front end of the tube and extending outward from the center, is severed and the tube is opened.
For properly fulfilling its function with film tube materials used in practice, the known arrangement requires a comparatively sharp blade which is regularly obtained only by a separate piece of metal mounted in the cap. This increases the cost of the device, which is regularly formed as a disposable part.
When the blade is formed as a stationary element, it prevents a piston from being fully advanced for completely emptying the tube.
In a further device known from German Offenlegungsschrift No. 3,826,887, the film tube is punctured by a spike which must be manually inserted, prior to the emptying step, through a discharge pipe provided on the cap, and must be withdrawn thereafter. This manipulation is not only cumbersome and time-consuming but also involves the danger that the container content is discharged prematurely, thereby contaminating the surroundings and/or being itself inadmissibly contaminated by foreign substances. Moreover, the known device is unsuited for use in power-operated discharging apparatus.